1. Field of the Invention
The present invention relates to a suspension system for use with a surgical microscope and, more particularly, to such a suspension system that maintains the surgical microscope in a balanced state for ease of motion.
2. Setting of the Invention
In the field of medical technology there exists a need for a mobile surgical microscope suspension system that permits the rapid and nearly effortless movement of the microscope when desired, as well as the firm fixation of the microscope when desired. Ideally, such a suspension system would have minimal mass and dimensions, a maximal number of positions for the microscope, uniformity of applied force for movement in all directions, reliable fixation in desired positions, and absence of spontaneous motion in an unlocked state.
Existing surgical microscope suspension systems are of relatively large size to provide desired mass and rigidity. However, this mass results in an increased moment of inertia so movement is difficult to precisely control. Usually, these surgical microscope suspension systems include costly and complex arrangements of counterbalances and springs. These systems have a problem of differences in the amount of force that need be applied to move the microscope in different directions, and a problem of spontaneous spring-induced movement when the system is unlocked.
Examples of prior types of suspension systems are disclosed in U.S. Pat. Nos. 3,762,797 and 3,891,301. These systems include a massive base and relatively large counterweight system used to provide stability to the microscope when in the unlocked position. In order to move the microscope in various directions, various amounts of force are required and a significant inertial force interferes with the precise positioning of the microscope.
The Olympus OME 5000 includes a massive base and a plurality of levers to maintain the microscope in a given position when the system is in the unlocked state. Again, various amounts of force are required to move the microscope in various directions.
Another type of microscope suspension system is disclosed in Soviet Union Scientific Research Institute of Governmental Patent Expertise, No. 0142 (1990), "Microscope For Neurosurgery" developed by the inventor hereof. This system still has the disadvantage of the differences of the amount of force needed to move the microscope in various directions. Other suspension systems are disclosed in the following U.S. Pat. Nos.: 3,973,748; 4,523,732; 4,741,607; 4,815,832; 4,881,709 and 4,953,822.